Born : c.
858 CE, Harran, Bilad al-Sham
Died : 929
CE, Qasr al-Jiss, near Samarra
Main :
Mathematics, Astronomy, Astrology.
Abū ʿAbd Allāh Muḥammad ibn Jābir ibn Sinān al-Raqqī
al-Ḥarrānī aṣ-Ṣābiʾ al-Battānī (Arabic: محمد بن جابر بن سنان البتاني)
(Latinized as Albategnius, Albategni or Albatenius) (c. 858 – 929) was an Arab
astronomer, astrologer, and mathematician. He introduced a number of
trigonometric relations, and his Kitāb az-Zīj was frequently quoted by many
medieval astronomers, including Copernicus.
Often called the "Ptolemy of the Arabs",
al-Battani is perhaps the greatest and best known astronomer of the medieval Islamic
world.
Life
Little of al-Battānī's life is known other than his
birthplace in Harran near Urfa, in Upper Mesopotamia, (today in Turkey) and his
father's fame as a maker of scientific instruments. Ibn Khallikan expresses
ignorance on the question of his Muslim faith, and points out that his epithet
aṣ-Ṣabi’ suggests possible Sabian-sect ancestry. Some western historians claim
he had noble origins as an Arab prince, but traditional Arabic biographers make
no mention of this. Between 877 and 918/19, over a forty-year period, he lived
in the ancient city of Raqqa, in north central Syria, recording his
astronomical observations. He is said to have died while returning to Baghdād
at a fortress called Kasr al-Hadr, which was near either Tikrit, or Samarra.
Astronomy
One of al-Battānī's best-known achievements in
astronomy was the determination of the solar year as being 365 days, 5 hours,
46 minutes and 24 seconds, which is only 2 minutes and 22 seconds off.
The twelfth-century Egyptian encyclopedist al-Qifṭī,
in his biographical history Ta’rīkh al-Ḥukamā’, mentions al-Battānī’s
contribution to advances in astronomical observation and calculations based on
Ptolemy’s Almagest.
Al-Battānī amended some of Ptolemy's results and
compiled new tables of the Sun and Moon, long accepted as authoritative. Some
of his measurements were more accurate than ones taken by Copernicus many
centuries later and some ascribe this phenomenon to al-Battānī's location lying
closer to the equator such that the ecliptic and the Sun, being higher in the
sky, are less susceptible to atmospheric refraction. Al-Battānī observed that
the direction of the Sun's apogee, as recorded by Ptolemy, was changing.
Among his Innovations
Introduction of
the use of sines in calculation and partially that of tangents.
Calculation of the values for the precession of the
equinoxes (54.5" per year, or 1° in 66 years) and the obliquity of the
ecliptic (23° 35').
Use of a uniform rate for precession in his tables,
choosing not to adopt the theory of trepidation attributed to his colleague
Thabit ibn Qurra.
Al-Battānī's work was instrumental in the development
of science and astronomy. Copernicus, in his book that initiated the Copernican
Revolution, the De Revolutionibus Orbium Coelestium, quotes his name no fewer
than 23 times, and also mentions him in the Commentariolus. Tycho Brahe,
Riccioli, Kepler, Galileo and others frequently cited him or his observations.
His data is still used in geophysics. The major lunar crater Albategnius is
named in his honor.
Mathematics
In mathematics, al-Battānī produced
a number of trigonometrical relationships:
He also solved the equation sin x = a cos x discovering
the formula:
He gives other trigonometric formulae for right-angled triangles such as:
Al-Battānī used al-Marwazi's idea
of tangents ("shadows")
to develop equations for calculating tangents and cotangents, compiling tables
of them. He also discovered the reciprocal functions of secant and cosecant,
and produced the first table of cosecants, which he referred to as a
"table of shadows" (in reference to the shadow of a gnomon), for each degree from 1°
to 90°.
Sumber
Labels:
Mathematician
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